Soil Contamination by Phthalate Esters in Cultivated and Non-Cultivated Soils in North African Arid Regions: A Tunisian Case Study

Abstract

Over the last decades, several studies showed that phthalic acid esters (PAEs) were ubiquitous environmental contaminants and became a major threat to human health. This study provided the first case study about the concentration and the potential sources of soil’s PAEs, both in Tunisia and North Africa. Soil samples were collected from four cultivated (CS) and two adjacent native soils (NS) at 0-10 cm and 10-30 cm layers in southeastern Tunisia. The PAEs concentrations were analyzed using a gas chromatography-mass spectrometry (GC-MS) system. Results showed that the total concentration of PAEs ranged from 2.40 to 11.05%. Higher values were detected in NS in the 0-10 cm layer contrary to CS which showed higher PAEs concentration in 10-30 cm depth. The di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) were the most abundant PAEs. In the 0-10 cm layer, PAEs concentration was highly related to the age of the plastic film in CS. We observed a positive association between PAEs concentration and conductivity (EC) values. The PAEs concentrations were affected by the presence of soil organic matter (SOM) in CS. This decrease of PAEs in CS compared to the NS may be related to the microbial decomposition activity stimulated by the presence of fresh organic residues and fertilizers. These results showed that CS and adjacent NS in the studied regions were contaminated by PAEs which is probably a result of agricultural activities. More investigations on PAEs concentrations in various soil managements are needed to confirm these results.